Based on the theory of liquid injector dynamics

the dynamic response of coaxial injector mixing ratio to the pressure pulsation in combustion chamber was theoretically studied

and the transfer function between the mixing ratio pulsation and combustion chamber pressure pulsation was also derived. The amplitude-frequency characteristics of the transfer function were calculated with a model liquid oxygen-kerosene bipropellant injector. Results showed that as the pulsation frequency increased

the pulsation amplitude of mixing ratio increased first

then decreased. The amplitude of transfer function increased when the supply system pressure increased

and decreased when the injector pressure drop increased. The frequency corresponding to the maximum amplitude was independent of supply system pressure and injector pressure drop

meaning that this frequency was dependent on the injector characteristics.